I hope to add to this list in the upcoming years as I visit more abnormal, spherical, rock formations. These spheres in Argentina and New Zealand seem to be naturally made. Some areas have ones more suspect. They are still wonders even if natural.
Wind blown desert boulders of Ichigualasto Argentina
Above taken with a film camera in 2003 the wind blown spheres of Ichigualasto Argentina. I took a day trip to the park from San Juan Argentina reached by bus from Mendoza. The park as a whole is an interesting UNESCO site with fossils old even by dinosaur fossil standards. I was mesmerized by these spheres just sitting out in the sand.
Moeraki Boulders New Zealand
Spheres on the beach in New Zealand. I drove down to have a look when I was staying in the fun Victorian/Steampunk town of Oamaru New Zealand on the south Island. These were actually on the beach and constantly covered by tides very different scenario than in Argentina.
Rock City, Kansas USA
These are giant spherical concretions. Geologists believe they form around something within the softer rock then the softer rock erodes away. However it sounds like they are not that sure. These mysteries giant spheres are hanging out in the Kansas Plains. Is there something at the center? Why here?
These are by far the largest I have seen.
Native Americans referred to them as Thunderbird Eggs.
How did these not make the 8 wonders of Kansas list? It is such an unusual and wonderous occurrence.